mirror of
https://github.com/DoctorWkt/unix-jun72.git
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54 lines
1.6 KiB
Plaintext
54 lines
1.6 KiB
Plaintext
cmpb i.uid,u.uid / is user same as owner of file
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hne 1f / no, then branch
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asrb r2 / shlft owner read write bits into non owner
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/ read/write blts
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asrb r2
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1:
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bit r2,(r0)+ / test read—wr1te flags agalnst argument Ln
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/ access call
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bne 1f
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tstb u.uid
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beq 1f
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jmp error
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1:
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rts r0
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setimod:
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movb $1,imod / set current i—node modified bytes
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mov s.time,i.mtim / put present tlme into file modified time
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mov s.time+2,i.mtim+2
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rts r0
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imap: / get the byte that has the allocation bit for the i—number contained
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/in r1
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mov $1,mq / put 1 in the mq
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mov r1,r2 / r2 now has i—number whose byte in the map we
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/ must find
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sub $41.,r2 / r2 has i-41
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mov r2,r3 / r3 has i-41
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blc $!7,r3 / r3 has (i-41) mod 8 to get the bit position
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mov r3,lsh / move the 1 over (i-41) mod 8 positions to the left
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/ to mask the correct bit
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asr r2
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asr r2
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asr r2 / r2 has (i-41) base 8 of the byte no. from the start of
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/ the map
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mov r2,-(sp) / put (i-41) base 8 on the stack
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mov $systm,r2 / r2 points to the in-core image of the super
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/ block for drum
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tst cdev / is the device the disk
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beg 1f / yes
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add $mount—systm,r2 / for mounted device, r2 points to 1st word
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/ of its super block
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1:
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add (r2)+,(sp) / get byte address of allocation bit
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add (sp)+,r2 / ?
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add $2,r2 / ?
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rts r0
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iget:
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cmp r1, ii / r1 = i-number of current flle
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bne 1f
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cmp idev,cdev / ls device number of i-node = current device
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beq 2f
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1:
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tstb imod / has i-node of current file been modified i.e.,
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/ lmod set
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